The proposed study, Outcomes of Sleep Disorders in Older Men, will take advantage of the established cohort that has been recruited for the Osteoporotic Fractures in Men (MrOS) study (5U01AR045647 - Dr. Eric Orwoll, PI) to address a number of questions regarding the role of sleep disorders in the pathogenesis of chronic illnesses and functional disability. MrOS, a 7-year study that began in July 1999, is a multi-center prospective study of approximately 6000 men aged 65 and older. During the MrOS baseline visit, a broad variety of measurements were collected, including body composition and body fat distribution (by DEXA and quantitative computed tomography), bone density, anthropometry, performance-based tests of strength and balance, medical history, medication use, smoking and alcohol use, and other parameters. Blood, urine, and DNA specimens have been archived for use in future studies of importance to the health of older men. In a subcohort of 3000 MrOS participants, we propose to add comprehensive and accurate assessments of sleep using in-home polysomnography, wrist actigraphy, questionnaires and other measures; and prospective adjudication of CVD events, to the extensive measures that have already been performed or planned in the MrOS cohort study. These new measures will enable us to test several important hypotheses: 1) To characterize the associations between sleep disruption and subsequent CVD events during 3.5 years of follow-up; 2) To determine if sleep disturbances are associated with an increased risk of total and cause-specific mortality in older men; 3) To test whether sleep disturbances are associated with increased risk of falls and decreased physical function; 4) To test whether sleep disturbances are associated with impaired cognitive function in older men; 5) To test whether sleep disorders are associated with bone density and fracture risk in older men. We will also supplement the bank of MrOS specimens to allow for testing of future hypotheses concerning the role of sleep in the development of age-related diseases and conditions. This application is for Case Western Reserve University to serve as a central PSG Reading Center for the proposed study. In this capacity, we will: a. Provide centralized training for aspects of MrOS related to the performance and interpretation of sleep studies. b. Provide ongoing technical support to the clinical sites for the performance of sleep studies; c. Provide timely review (for quality and medical alerts) and scoring of all records, generating reports needed for participant feedback and data analysis; d. Participate in on-going quality assurance efforts to maintain high levels of scoring accuracy and reliability; e. Develop, implement and monitor the technical performance of PSGs at the clinical field sites.